Contributing a Rock-on

Rock-ons are Docker plugins (see Rock-ons (Docker Plugins) for more information) defined by a JSON file stored in the rockon-registry repository on

How can I add my own Rock-on?

As already detailed in the Adding your own Rock-on section, if you are familiar with Docker and know how to run apps by hand, you can create a Rock-on for the same with a little bit of craft. There are three broad steps:

1. Configure the Rock-on service on your Rockstor system. Follow the steps described here Rock-ons (Docker Plugins).

2. Create your Rock-on profile file, [app].json following the clues on the Rock-on structure described in the Rock-on repository

3. Upload the file to /opt/rockstor/rockons-metastore/[app].json. Hit update in the Web-UI and install your brand new Rock-on!

If you would like to share your app with the rest of the Rockstor community, open an issue describing what you are trying to contribute and then a subsequently linked pull request in this repository. Please follow these guidelines when opening a pull request:

1. One Rock-on per pull request please. If you are working on multiple apps, separate them out. It will make testing and merging a lot more manageable.

2. Add a comment to your pull request detailing how you’ve tested it out. Link to the previously created issue. The more details the better as it will help ensure quality and benefit the whole community!

3. We are trying to offer Rock-ons that are based on a multi-architecture docker image, i.e., it is available for amd64 (Intel/AMD CPUs) and arm64 (ARM-based) devices. While that might not always be possible, depending on the app or service which you are interested in, please keep that in mind and see whether you can select a docker image that has a multi-architecture manifest. When submitting, please add the supported architectures to the end of the Rockon description using the <p> and </p> tags (take a look at the descriptions of some of the more recent Rock-on submissions).

Adding vs. updating a Rock-on

While there are no hard and fast rules, you can follow these guidelines to decide whether it is better to update an existing Rock-on or submit a new one that contains substantial changes:

1. If no Rock-on exists for your app already, create a new one. The obvious choice.

2. Create a new Rock-on if one already exists for this project, but the new one will use a different docker image. E.g., an existing Rock-on uses an image from, while the one you are interested in submitting uses an image created by the owner of the project. You can subsequently submit a proposal to deprecate the existing Rock-on. Reasons for that could be that the underlying docker container has not been maintained in a long time, or the new Rock-on will have the same or more functionality and is more popular with the community.

3. Update the existing Rock-on if the changes do not include the use of a different image. E.g., the Handbrake Rock-on was expanded with a few useful user parameters over time, but continued to use the same underlying docker image. Here it made more sense to update the existing Rock-on instead of submitting a new version.

Which Docker image should I use?

Docker hub centralizes a very large number of docker images. As a result, it can sometimes be difficult to select the best image among dozens for very popular projects. While it is nearly impossible to provide a simple “rule” for selecting the best image, the best image for a Rock-on will be secure, maintained in the long-term, compatible with Rockstor, and allow for “all-in-one” use for the end-user. In this context, the following guidelines can help:

  • Is there an official image for your project of interest? Official images are clearly labeled in Docker hub and provide assurance with regards to security, and long-term maintenance of the image.

  • Does the project provide its own docker image? These usually ensure the good quality of the image and best experience with the respective project.

  • Is the image regulary updated? Generally, an image with active maintainer(s) and community will be able to offer better support and timely updates. The image history on its Docker hub page as well as the number of pulls/favorites can be a useful indicator of an active image.

  • Does the image allow for an “all-in-one” user experience? Ideally, the image would allow for an easy install from the Rockstor’s webUI without requiring user intervention at the command line before and/or after.

  • Finally, the image size is another helpful factor, with smaller images being usually favored.

Environment setup

Go to the rockon-registry repo and click on the Fork button. This will fork the repository into your profile which serves as your personal git remote called origin. The next few git steps are demonstrated on a Linux terminal.

Create a local clone of your fork.

git clone

Configure this new git repo with your name and email address. This is required to accurately record collaboration.

cd rockon-registry
git config "Firstname Lastname"
git config your_email_address

Add a remote called upstream to periodically rebase your local repository with changes in the upstream made by other contributors.

git remote add upstream

The above 4 steps help you setup your local environment. If you are familiar with git and use an IDE, you can achieve the same outcome in a different way. Here, we listed the simple terminal way of setting it up.

Steps to Contribute a Rock-on with a Pull Request

Rebase your master branch before making your own changes.

cd rockon-registry
git checkout master
git pull --rebase upstream master

Checkout a new/separate branch for your Rock-on

git checkout -b rockon_name

Add and commit your Rock-on to git. Say you are updating the Syncthing Rock-on and have the syncthing.json tested and ready to go. First copy the file over to your repo. Next,

git add syncthing.json
git commit -m 'update syncthing rock-on'

When adding a new Rock-on, e.g. based on the fictious moonshine docker image and created the new file moonshine.json, also add the name of this file (case-sensitive) to the root.json file (it’s alphabetically sorted). This means you add both files to the commit,

git add moonshine.json root.json
git commit -m 'add moonshine rock-on`

Now you can push your Rock-on to github. <branch_name> is from above where you checked out a new branch.


When updating to a new version (as mentioned in scenario 2 in the Adding vs. updating a Rock-on section, first submit a pull request adding the new Rock-On (you will have to use a slightly different name). Then follow the Deleting a Rock-on process. This way, the history more clearly represents what transpired with this Rock-on.

git push origin <branch_name>

Now you can go to github, open an issue on the rockstor repo if you have not done so already that describes the Rock-on that you were working on and then open a pull request from your forked repo, populate it with the requested info (e.g., link it to a previously opened issue) and submit it.

Deleting a Rock-on

The Rock-ons repository is predominantly community maintained/led. As such we depend on community involvement to maintain its health. On occasions a Rock-on will fall into disrepair. If you find such a Rock-on, i.e. broken or built on an abandoned/deprecated docker image, then please report this on our friendly forum. If there is then no community will/effort to maintain/repair that rock-on, then we will happily accept a pull request to delete it. Such a pull request would include the removal/deletion of the associated JSON definition file and its associated entry within the root.json file. Please reference the relevant forum discussion upon submitting such a pull request and limit each such Rock-on delete request to a single Rock-on. Such ‘weeding’ is definitely encouraged and contributes to the overall health of this repository and the project as a whole. It’s always frustrating to find something broken and if the community will is not there to repair it, then it’s best removed. We have in the past neglected to stress this side of the community maintenance ‘feedback’ and are now moving to actively encourage this much needed ‘weeding’.